NOAA, NASA: Significant ozone hole remains over Antarctica October 20, 2011 Ozone levels in the atmosphere above the South Pole dropped to a seasonal low of 102 Dobson Units Oct. 9, tied for the 10th lowest in the 26-year record. The ozone layer helps protect the planet’s surface from harmful ultraviolet radiation. Every year, an ozone hole forms above the Antarctic for several weeks, because of environmental conditions and the presence of ozone- depleting chemicals. High Resolution (Credit: NOAA) The Antarctic ozone hole, which yawns wide every Southern Hemisphere spring, reached its annual peak on September 12, stretching 10.05 million square miles, the ninth largest on record. Above the South Pole, the ozone hole reached its deepest point of the season on October 9 when total ozone readings dropped to 102 Dobson units, tied for the 10th lowest in the 26-year record. The ozone layer helps protect the planet’s surface from harmful ultraviolet radiation. NOAA and NASA use balloon-borne instruments, ground instruments, and satellites to monitor the annual South Pole ozone hole, global levels of ozone in the stratosphere, and the manmade chemicals that contribute to ozone depletion. “The upper part of the atmosphere over the South Pole was colder than average this season and that cold air is one of the key ingredients for ozone destruction,” said James Butler, director of NOAA’s Global Monitoring Division in Boulder, Colo. Other key ingredients are ozone- depleting chemicals that remain in the atmosphere and ice crystals on which ozone-depleting chemical reactions take place. “Even though it was relatively large, the size of this year's ozone hole was within the range we'd expect given the levels of manmade, ozone-depleting chemicals that continue to persist," said Paul Newman, chief atmospheric scientist at NASA's Goddard Space Flight Center. http://www.noaanews.noaa.gov/stories2011/images/spole_totaloz_2011_oct12.png http://www.noaanews.noaa.gov/stories2011/images/spole_totaloz_2011_oct12.png Levels of most ozone-depleting chemicals are slowly declining due to international action, but many have long lifetimes, remaining in the atmosphere for decades. Scientists around the world are looking for evidence that the ozone layer is beginning to heal, but this year’s data from Antarctica do not hint at a turnaround. In August and September (spring in Antarctica), the sun begins rising again after several months of darkness. Circumpolar winds keep cold air trapped above the continent, and sunlight-sparked reactions involving ice clouds and manmade chemicals begin eating away at the ozone. Most years, the conditions for ozone depletion ease by early December, and the seasonal hole closes. NOAA researchers at the South Pole release a ballonsonde, a massive balloon carrying instruments that measure ozone, temperature, humidity and more from the surface of the snow to about 20 .

1. NOAA, NASA: Significant ozone hole remains over
Antarctica
October 20, 2011
Ozone levels in the atmosphere above the South Pole dropped to
a seasonal low of 102 Dobson
Units Oct. 9, tied for the 10th lowest in the 26-year record. The
ozone layer helps protect the
planet’s surface from harmful ultraviolet radiation. Every year,
an ozone hole forms above the
Antarctic for several weeks, because of environmental
conditions and the presence of ozone-
depleting chemicals.
High Resolution (Credit: NOAA)
The Antarctic ozone hole, which yawns wide every Southern
Hemisphere spring, reached its
annual peak on September 12, stretching 10.05 million square
miles, the ninth largest on record.
Above the South Pole, the ozone hole reached its deepest point
of the season on October 9 when

2. total ozone readings dropped to 102 Dobson units, tied for the
10th lowest in the 26-year record.
The ozone layer helps protect the planet’s surface from harmful
ultraviolet radiation. NOAA and
NASA use balloon-borne instruments, ground instruments, and
satellites to monitor the annual
South Pole ozone hole, global levels of ozone in the
stratosphere, and the manmade chemicals
that contribute to ozone depletion.
“The upper part of the atmosphere over the South Pole was
colder than average this season and
that cold air is one of the key ingredients for ozone
destruction,” said James Butler, director of
NOAA’s Global Monitoring Division in Boulder, Colo. Other
key ingredients are ozone-
depleting chemicals that remain in the atmosphere and ice
crystals on which ozone-depleting
chemical reactions take place.
“Even though it was relatively large, the size of this year's
ozone hole was within the range we'd
expect given the levels of manmade, ozone-depleting chemicals
that continue to persist," said
Paul Newman, chief atmospheric scientist at NASA's Goddard
Space Flight Center.

3. http://www.noaanews.noaa.gov/stories2011/images/spole_totalo
z_2011_oct12.png
http://www.noaanews.noaa.gov/stories2011/images/spole_totalo
z_2011_oct12.png
Levels of most ozone-depleting chemicals are slowly declining
due to international action, but
many have long lifetimes, remaining in the atmosphere for
decades. Scientists around the world
are looking for evidence that the ozone layer is beginning to
heal, but this year’s data from
Antarctica do not hint at a turnaround.
In August and September (spring in Antarctica), the sun begins
rising again after several months
of darkness. Circumpolar winds keep cold air trapped above the
continent, and sunlight-sparked
reactions involving ice clouds and manmade chemicals begin
eating away at the ozone. Most
years, the conditions for ozone depletion ease by early
December, and the seasonal hole closes.
NOAA researchers at the South Pole release a ballonsonde, a
massive balloon carrying
instruments that measure ozone, temperature, humidity and

4. more from the surface of the snow to
about 20 miles high.
High Resolution (Credit: NOAA)
Levels of most ozone-depleting chemicals in the atmosphere
have been gradually declining since
an international treaty to protect the ozone layer, the 1987
Montreal Protocol, was signed. That
international treaty caused the phase out of ozone-depleting
chemicals, then used widely in
refrigeration, as solvents and in aerosol spray cans.
Global atmospheric models predict that stratospheric ozone
could recover by the middle of this
century, but the ozone hole in the Antarctic will likely persist
one to two decades beyond that,
according to the latest analysis by the World Meteorological
Organization, the 2010 Ozone
Assessment, with co-authors from NOAA and NASA.
Researchers do not expect a smooth, steady recovery of
Antarctic ozone, because of natural ups
and downs in temperatures and other factors that affect
depletion, noted NOAA ESRL scientist
Bryan Johnson. Johnson helped co-author a recent NOAA paper
that concluded it could take

5. another decade to begin discerning changes in the rates of ozone
depletion.
Johnson is part of the NOAA team tracks ozone depletion
around the globe and at the South Pole
with measurements made from the ground, in the atmosphere
itself and by satellite. Johnson’s
“ozonesonde” group has been using balloons to loft instruments
18 miles into the atmosphere for
http://www.noaanews.noaa.gov/stories2011/images/2011ozones
onde12.jpg
http://www.noaanews.noaa.gov/stories2011/images/2011ozones
onde12.jpg
26 years to collect detailed profiles of ozone levels from the
surface up. The team also measures
ozone with satellite and ground-based instruments.
This November marks the 50th anniversary of the start of total
ozone column measurements by
the NOAA Dobson spectrophotometer instrument at South Pole
station. Ground-based ozone
column measurements started nearly two decades before the
yearly Antarctic ozone hole began
forming, therefore helping researchers to recognize this unusual
change of the ozone layer.

6. NASA measures ozone in the stratosphere with the Ozone
Monitoring Instrument (OMI) aboard
the Aura satellite. OMI continues a NASA legacy of monitoring
the ozone layer from space that
dates back to 1972 and the launch of the Nimbus-4 satellite.
A new satellite scheduled to launch this month, the NPP
satellite, features a new ozone-
monitoring instrument, the Ozone Mapping and Profiler Suite,
which will provide more detailed
daily, global ozone measurements than ever before to continue
the task of observing the ozone
layer's gradual recovery. The NPP satellite is part of Joint Polar
Satellite System, a program of
NOAA, NASA and the Department of Defense (formerly known
as the NPOESS Preparatory
Project). It is scheduled to launch October 27 from Vandenberg
Air Force Base in California.
NOAA’s mission is to understand and predict changes in the
Earth's environment, from the
depths of the ocean to the surface of the sun, and to conserve
and manage our coastal and marine
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